Heretofore, a method for manufacturing a three-dimensional shaped object by irradiating a powder with a light beam has been known (such method can be generally referred to as “selective laser sintering method”). Such method can produce a three-dimensional shaped object with a plurality of solidified layers stacked integrally by repeating the step (i) of forming a solidified layer by irradiating a predetermined portion of a powder layer with a light beam, thereby allowing sintering of the predetermined portion of the powder or melting and subsequent solidification thereof, and the step (ii) of forming another solidified layer by newly forming a powder layer on the resulting solidified layer, followed by similarly irradiating the powder layer with the light beam (see JP-T-01-502890 or JP-A-2000-73108). The three-dimensional shaped object thus obtained can be used as a metal mold in a case where inorganic powder materials such as a metal powder and a ceramic powder are used as the powder material. While on the other hand, the three-dimensional shaped object can be used as a model or replica in a case where organic powder materials such as a resin powder and a plastic powder are used as the powder material. This kind of technology makes it possible to produce the three-dimensional shaped object with a complicated contour shape in a short period of time.
By way of the case of using a metal powder as a powder material and using the resulting three-dimensional shaped object as metal mold, as shown in FIG. 1, a powder layer 22 with a predetermined thickness t1 is firstly formed on a base plate for shaped object 21 (see FIG. 1(a)) and then a predetermined portion of a powder layer 22 is irradiated with a light beam to form a solidified layer 24 on base plate for shaped object 21. Then, a powder layer 22 is newly provided on the solidified layer 24 thus formed and is irradiated again with the light beam to form another solidified layer. In this way, when the solidified layers are repeatedly formed, it is possible to obtain a three-dimensional shaped object with a plurality of solidified layers 24 stacked integrally (see FIG. 1(b)).    PATENT DOCUMENT 1: JP-T-01-502890    PATENT DOCUMENT 2: JP-A-2000-73108